DESCRIPTION (Abstract of the Core) The Radioimmunoassay and Biochemistry Core serves as an essential and important function of this Program Project. We have a long history with these investigators in providing antisera and radioimmunoassays for gut and calcium regulatory peptides. We have a unique capacity of interfacing with each project and producing highly specific antisera and radioimmunoassays in a cost effective manner. The primary purpose of the Radioimmunoassay and Biochemistry Core Laboratory is to provide for measurement of gut regulatory peptides, calcium-regulatory related peptides (ie, PTHrP) and CGA-related peptides in an efficient, cost effective and controlled manner for the investigators who participate in this Program Project. Table 1 shows the current use of Core B by Projects 1-4. For instance, during a 12-month period (January through December 1999) we processed approximately 17,000 tubes (see Table 2). We generated several antisera for luminal CCK-releasing (LCRF) factor. We prepared affinity-purified LCRF antisera that are used to make affinity columns, and we have assisted in preparation of LCRF affinity columns which are used in Project 2. We have generated new neurotensin and chromogranin A (CGA) antisera for neurotensin and CGA RIAs that are used in Projects 1 and 3. We have generated prohormone convertase-5 (PC-5) antisera that are used for Western blotting and immunoneutralization in Project 2. We continue to assist with Project 3 in the preparation of radioiodinated ligands (i.e., gastrin) for binding assays. For Project 4, we will provide reagents for PTHrP measurement, PTHrP antisera for Western and immunohistochemistry and selected antisera for apoptosis-related proteins (Bcl-2, Bax, caspases).